A comprehensive review of frequency response and control strategies for grid-connected solar photovoltaic systems

Renewable energy is the future of energy generation to meet the growing electricity demand worldwide. The extensive integration of Renewable Energy Sources (RESs) is causing a paradigm shift in the power network. Integrating RESs reduces the overall inertia of the system, which could result in occasional unstable frequency and may lead to cascading blackouts. This paper performs an overarching analysis of different frequency control techniques that support seamless integration of solar photovoltaic systems to the grid. These techniques are extensively compared based on various parameters and are categorised based on control actions and implementation to highlight their effectiveness and limitations. Before exploring frequency regulation methods, a primer on PV system modelling and configuration is given to comprehend PV integration to the grid. Furthermore, a brief synopsis of strategies utilising Energy Storage Devices (ESSs) is provided, emphasising methods that do not require ESSs. Beyond this, an overview of optimisation algorithms used in the literature for frequency regulation is given, providing a holistic understanding. Recent research highlights the growing interest in hybrid power reserve approaches, as combining diverse optimisation algorithms offers robust, reliable, fast, and adaptive solutions. This paper endeavours to provide a holistic review for researchers interested in developing frequency regulation methods for PV systems and to support industry practitioners in finding the appropriate solutions for frequency regulation-related applications.